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[browser] make dynamic import cancelable #80257

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merged 3 commits into from
Jan 6, 2023
Merged

[browser] make dynamic import cancelable #80257

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3250fc0
make dynamic import cancelable
pavelsavara Jan 5, 2023
5579a72
Merge branch 'main' into browser_ImportAsync_cancelable
pavelsavara Jan 6, 2023
622fa5e
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pavelsavara Jan 6, 2023
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10 changes: 10 additions & 0 deletions ...ices.JavaScript.UnitTests/System/Runtime/InteropServices/JavaScript/JSImportExportTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
using System.IO;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;
using System.Threading;
using Xunit;
#pragma warning disable xUnit1026 // Theory methods should use all of their parameters

Expand All @@ -31,6 +32,15 @@ public async Task MultipleImportAsync()
Assert.Same(instance1, instance2);
}

[Fact]
public async Task CancelableImportAsync()
{
var cts = new CancellationTokenSource();
cts.Cancel();
var actualEx = await Assert.ThrowsAsync<JSException>(async () => await JSHost.ImportAsync("JavaScriptTestHelper", "./JavaScriptTestHelper.mjs", cts.Token));
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  • Is there a way to reliably test that the operation gets cancelled in the middle? Passing an already cancelled token is a trivial case that is optimized in other asynchroonous functions. (and you can use new CancellationToken(true) instead of creating a CTS)
  • Shouldn't it throw OperationCancelledException?

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The underlying JS dynamic import() is not cancelable.
The JS promises are rather "abandoned" than really canceled. We only reject the JS promise.
(In general, we don't know what else registered continuation on that promise on JS side)

That creates JavaScript error, not managed error and we marshal it as JSException consistently with all other JS Errors.

fetch is bit better because it has AbortController.

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@maraf maraf Jan 6, 2023 •
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@pavelsavara Did you tried something like this?

var cts = new CancellationTokenSource();
var exTask = Assert.ThrowsAsync<JSException>(async () => await JSHost.ImportAsync("JavaScriptTestHelper", "./JavaScriptTestHelper.mjs", cts.Token));

cts.Cancel();

var actualEx = await exTask;

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added to the unit test, it works fine

Assert.Equal("OperationCanceledException", actualEx.Message);
}

[Fact]
public unsafe void GlobalThis()
{
Expand Down
20 changes: 12 additions & 8 deletions src/mono/wasm/runtime/invoke-js.ts
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Expand Up @@ -13,6 +13,7 @@ import { mono_wasm_new_external_root } from "./roots";
import { mono_wasm_symbolicate_string } from "./logging";
import { mono_wasm_get_jsobj_from_js_handle } from "./gc-handles";
import { endMeasure, MeasuredBlock, startMeasure } from "./profiler";
import { wrap_as_cancelable_promise } from "./cancelable-promise";

const fn_wrapper_by_fn_handle: Function[] = <any>[null];// 0th slot is dummy, we never free bound functions

Expand Down Expand Up @@ -317,7 +318,7 @@ export function get_global_this(): any {
export const importedModulesPromises: Map<string, Promise<any>> = new Map();
export const importedModules: Map<string, Promise<any>> = new Map();

export async function dynamic_import(module_name: string, module_url: string): Promise<any> {
export function dynamic_import(module_name: string, module_url: string): Promise<any> {
mono_assert(module_name, "Invalid module_name");
mono_assert(module_url, "Invalid module_name");
let promise = importedModulesPromises.get(module_name);
Expand All @@ -328,13 +329,16 @@ export async function dynamic_import(module_name: string, module_url: string): P
promise = import(/* webpackIgnore: true */module_url);
importedModulesPromises.set(module_name, promise);
}
const module = await promise;
if (newPromise) {
importedModules.set(module_name, module);
if (runtimeHelpers.diagnosticTracing)
console.debug(`MONO_WASM: imported ES6 module '${module_name}' from '${module_url}'`);
}
return module;

return wrap_as_cancelable_promise(async () => {
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const module = await promise;
if (newPromise) {
importedModules.set(module_name, module);
if (runtimeHelpers.diagnosticTracing)
console.debug(`MONO_WASM: imported ES6 module '${module_name}' from '${module_url}'`);
}
return module;
});
}


Expand Down